There may be several cases in which many wireless transmit/receive units (WTRUs) need to transmit a small amount of data, or to transmit data within a small time frame. This may depend on the type of application that these WTRUs are running. Thus, in general, there is a trend for WTRUs or applications that require transmission of small amounts of data to transmit that data, via a control plane, simply because the control plane has enough space to carry the data. Thus the establishment of a user plane and associated resource reservations may not be needed.
Moreover, using an Internet protocol (IP) address for each WTRU or for a group of WTRUs may consume many IP addresses. For example, in IPv4, there may be a limit to the size of an available IP address pool, and the number of WTRUs may exceed the number of available IP addresses. In addition, if an IP address were to be assigned to each WTRU, a lot of signalling may be required. Also, corresponding user plane resources may need to be setup and reserved. Thus, it may be useful to send data by other methods other than those requiring IP addresses.